Method and apparatus for forming molds and articles produced thereby



B. BART Aug. 16, 1932.

METHOD AND APPARATUS FOR FORMING MOLDS AND ARTICLES PRODUCED THEREBY Filed Oct. 28, 1 926 INVENTOR BY 65m Patented Aug. 16, 1932 BLASIUS BART, OF EAST ORANGE, NEW

TION, OF LONG ISLAND CITY, NEW YORK,

PATENT OFFICE JERSEY, assreuon. T was ram]: conroaa- A. CQBPORATION OI METHOD AND APPARATUS FOR FORMING HOLDS AND ARTICLES PBOD UGED THEBEBY The invention in the formherein selected for specifictreatment relates to aanethod of forming curved and other types of non-planctary surfaced molds which are subsequently utilized for the purpose of forming, for instance, metallic flanged parabolic reflectors and similar articles which contain curved and other forms of surfaces required to have a. mathematically exact configuration and which sometimes are required to possess a high degree of light reflection.

-The prlmary object of the invention is to provide a simplified means for forming exact facsimiles 'of a master mold and whlch facsimiles will beaccurateto molecular proportions; will not require polishing or other 1 and which treatment to receive the subsequent electrolytic deposition forming the finished article, will provide an accurately defined outline to thefinished article without neces sity of retrimming the outline or otherwise modifying the electroformed structure.

Another object of the invention is to provide a mold of electrolytically precipitated metal which will be either of uniform thick-.

ness, or ,in which'the thickness is graduated to give'requisite; strength at those portions of the mold-'where such strength is desired and to provide. a' technique of treatment which can be easily practiced and which feature economy both in the amount of ,material used and in the electric current consumption. 1 the apparatus feature ,Inconnection with of the disclosure an object of the invention is to provide a simple form of mounting for the master mold and'associated arts which- Application filed October 28, 1980. Serial No. 144,904.

signed to produce exactly the-desired workingmold, economically with the least loss in current consumed, with an avoidance of the formation of trees or thinned out layers or other undesired parts, and which W111 provide for an easy manipulation of the structure in mounting the parts in position therein and in providing for a regulated access of the electrolyte thereto when the parts are assembled in the electrolytic bath for the electro-forming of the article.

Various other objects and advantages of the invention will be obvious from a consideration of the preferred, method of practic-' ing the invention hereinafter described and from an inspection of 'the accompanying drawing and in part will be more forth'in the followin particular description of one method and of one form of apparatus for practicing the method and the invention also consists in certain new and novel operations and features of'construction and combination of and claimed.

' In the accompanying drawing:

Fig. 1 is a view partly in side elevation parts hereinafter set forth and partly in radial section of a master mold mounting with a parabolic form of working mold partially formed thereon and which figure illustrates a preferred embodiment of the apparatus feature of this also illustrates a step in the method feature of the disclosure; Fig. 2 is a fra the underside of t e structure shown in Fig; 1, it being understood that only one half of the circular form in plan of Fig. 1 is shown in this view; '1 Fig. 3 is an'enlarged sectional view with the coatings on the master mold exaggerated in thickness and constituting an enlargement of the showing at the left of Fig.1 with the clamping frame removed fromt e master and partially formed working mold; and

Fig. 4 is a sectional ,view corresponding to the showing inFig. 3 of the finished working mold with the master mold removed and showing thereon.

disclosure and" entary view in plan of I the finished reflector in position ully set goto makeup the working mo d produced thereon, and which apparatus will be de forming articles to be reproduced such as parabolic flan ed reflectors, it is necessary of course to rst prepare a master mold which is usually done by preparin a wax form which is copper coated, finis ed mechanically to the desired configuration and polished to a final finish. The formation of .to make a series of master molds. In the instant case one of such master molds is shown at .10, Fig. 1, and the method of prog which forms no part of the present duc ln disc osure. Insofar as the present disclosure is concerned it need be considered simply that the master mold is formed of or some similar conducting metal.

The illustrated form of master mold includes a central parabolic body portion 11 outlined by an outstanding flange 12 of somewhat greater width than the finished reflector which is to be formed on the working model herein featured. The inner face of the parabolic portion has a highly reflective surface. The body portion 11 is provided at the crown 12' with an aperture 13 in which is fitted a metallic connecting tip 14 by means of which current is conducted to the metal mold. When ready to be used the inner end of the 'connectcopper 111 1 tip is capped by means of a celluloid it is thimble 15 which acts to stop off the deposi- (tion from the metal connecting tip. The outer exposed portion of the mold 10 which is not Intended to be plated is covered with a coating 16 of insulating material preferably li -uid cellulose which in this instant exten s from the crown 12 to the outer edge 17 and across the u per or back side ofthe mold. The outstan ing flange 12 is provided on its under or exposed side with a ring locating groove 18. This groove is designed to locate the position relative to the mold of a preformed outlining frame, herein shown to be an endless ring 19. This ring is formed of .insulating material which at least has its outer exposed face of insulating material and in the instant case the ring is formed entirely' ofcelluloid. Before the ring is mounted in position it is slightly but completely coated with a thin and readily removable layer of conducting material 20. In actual practice most economical to coat the ring by Sp eof silver salt so that the layer -20 in the illustralte \case 'isa thin layer of metallic silver.

he i ing is flattened on its inner periphery and asiparticularly shown in Figs. 3 and 4 along a linea-b inclined to the axis of the ring. This inclined face 21 of the inner periphery of the ring is roughened as by being provided with a locking groove 22 particularly designed to assist in locking the ring ing the same with a reducing solution ness. In

to the electrolytically deposited layer here- -21. The cover plate 25 is positioned on top of the celluloid-back master mold 10 and the frame is tightened into clamping screws 27 spaced apart circumferentially of the clamping frame.v clamping screws are formed of metal, preferably brass, but the heads 29 and the nuts 30 at opposite ends are formed of insulating material, preferably celluloid.

With the parts thus assembled, the mold with its attached parts forming the assemblage shown in Fig. 1 is suspended in and subjected to the action of, an electrolytic bath. It is suggested that it be subjected, first, to the action of a bath containing nickel and in this case there is formed on the, metal exposed surfaces of the master mold 10, a thin layer 31 of nickel which will extend across the inner polished face of themaster mold 10 from the thimble 15 across the inner portion of theflange 12 and across the inclined face 21 of the ring up to the insulating seat 26. It is the present practice to deposit the nickel to about a thickness of one one-thousandth of an inch after which the assemblage is positioned in a copper containing bath where it is permitted to remain until the re uisite thickness of copper has formed. In t e instant case, this deposition is permitted to continue until there is a layer of copper of about one-eighth of an inch thick.

Under some conditions, the followin of this method as outlined would result 1;]; a greater thickness of deposit on the ring and adjacent portions of the flange with the thickness of depositionmore or less gradually decreasing towards the crown 12' where the deposit would be of minimum thickness. In order to prevent this and to insure a more uniform deposition over the entire exposed portion of the mold and the ring,the depositing action is partially stopped Qif'before the coppercoating has acquired its requisite thickthe instant case the assemblage,is removed from the copper bath after about one thirty-second of an inch of copper has formed on the flange 12,.and a stopping off or equalizingscreen is added to, the assemblage The shank portions 28 of the" III) - Referring to 1, there is shown an in outline with the outer portion'34 flat so mgscreen 33 ofinsulating-material is) I as to rest firmly against the under side of the clamping frame. The central portion of this screen is funnel shaped in form as shown at 35. This equalizing screen follows somewhat the configuration of .the surface of the mold being electroplated and is spaced therefrom so as to permit access of the electrolyte to all portions of the exposed surface of the mold and, ring even when the equalizing screen is in position. The funnel converges inwardly and up wardly as particularly shown in Fig. 1 and forms a somewhat restricted opening 36 concentric with and positioned below the thimble 15. This equalizing screen is demountably held in position on. the clamping frame by means of screen clamping screws 37 resembling in construction the frame clamping screws 27 and alternating with these screws about the circumference of the screen and frame.

With the screen in position there is a more active deposition of the copper or other elec troforming metal adjacent the crown portion of the master mold than at'the outer edges of the mold and in this way the natural tendency of the copper to accumulate adjacent the ring is compensated, and as aresult a substantially uniform layer of copper is depos ited across the exposed portion of the master mold. This precipitation layer of metal attaches itself at its outer edge firmly to the I silver coated celluloid ring 19 so that the ring and formed layer constitute a unit which is eventually removed from the master mold to form a working mold 38. When sufliciently formed the unit is removed from the clamping frame by loosening the screws 27 and 37 and separating the assembly from the metal -master mold which is usuallv facilitated by slightly heating the same. When free of the mastenmold, the working mold 38 contains on the part of the ring 19 which was not exposed to the electrolyte, the remnant of the silver layer 20 which is removed by washing the silver particles off and recovering the silver. The finished article with the celluloid ring exposed at its perimeter and herein identifieda's a working mold is subsequently used in Fig. 4, but the method of forming this finished reflector is no part of this disclosure.

It will be seen that the working mold 38 is an exact reproduction of the inner polished surface of the master mold from the crown '12 to the inner peripheral edge ofthe slot 18. To this accurately formed metal portion the celluloid ring 19 is secured by an electrolytic soldering action of the layer as it is formed. The ring acts during the formation of the finished reflector to outline and limit the outer peripheral edge 40 of the finished reflector. The celluloid ring not only defines the outline of the flange of the finished reflector but it also acts to strengthen and maintain the configuration of the working mold 38.

Should these working molds become damaged I flectors may be formed in large numbers as a factory production and without necessity of polishing either the finished reflectors or the molds on' which they are formed.

The partial stopping off after it has started tends to insure a uniform thickness of the deposited metal across the entire surface of the mold under treatment and eliminates the formation of trees and other irregularities which normally tend to form about the outlining ring.

While I have shown and described, and have pointed out in the annexed claims, certain novel-features of the invention, it be understood that various omissions, substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing tion. Y

Having thus described my invention, I claim:

1. In the art of forming workingmolds for flanged parabolic reflectors, the method which consists in securing a ring to one side ring, the portion of the flange and the parav bolic portion within the outlines of the ring thereby soldering the ring to the layer thus formed, and partially, but not entirely, stopof the deposition from the spirit of the invenwill 'ofthe flange of a flanged master mold, ex-

ping off the deposition from the portion of the mold adjacent the flange and ring while permitting the deposition to continue uninterrupted adjacent the center of the parabolic portion of the mold until the desired thickness of metal has formed.

2. In the art of forming working molds for subsequent use in formingjarticles by electrolytic deposition on the working molds, the method which consists in positioning on a master mold a preformed outlining frame of insulating material which has been temporarily coated with a readily removable conducting material. subjecting the master mold with the coated-frame thereon as cathode to the action of an electrolytic bath while stopping off the deposition from the outer portion of the frame, therebytoform the working mold with the frame soldered thereto at its perimeter and removing from the frame any exposed part of the precoated readi? removable conducting material.

the art of forming articles electrolytically, the method which consists in temporarily coating a frame of insulating material with a conducting material, locating said coated frame on a mold, subjecting the same as cathode to the action-of an electroiytic bath while stopping off the deposition rom a portion of the frame thereby to cause the deposited layer of metal to be soldered electrolytically to the frame and removing from the frame any portions of the coating material. o g 4. In the art of formin articles eletrolytically, the method whic consists in sub- ]e ting to the action of an electrolytic bath, a mold ascathode-to which is secured a pre- 3 formed frame thereby to cause the formation of a layer of metal on the mold and soldered to the frame, and then partially. stopping off the deposition of metal on to the portion of the mold adjacent the frame while permitting the electrolytic deposition on other parts of the mold.

5. A mold for use in forming flanged parabolic reflectors, including a central parabolic portion outlined by an outstanding a0 flange formed 'of electrolytically deposited metal, and. outlined by a frame secured to one. side to the outstanding flangeand havin its exposed portions defined by an in-. su ating s face.

" tral para 6. A device for usein forming flanged parabolic reflectors by'electrolytic preclpitation, com rising a metal mold havinga central para olic portion outlined bya flange integral therewith and provided on one side with a ring receiving groove, a ring demountably positioned in said groove and clamping means of insulating material for temporarily securing the ringfto the flange,

while leavmgportions of the mold and ring 45. ex osed.-

. A device for use in forming flan ed parabolic reflectors by electrolytic PIGClPltfi-"f Outlllled flange, means for temporarily securtion, comporising a metal mold having a cenlic portion outlined by aflange, ,cIamping means -.of insulatin material or tempprarily securing the ring to the flange, w le leaving portions of the mold and ring exposed, and an equalizing screen for incompletely stopping olf the electrolytic deposition from parts of the mold and ring.

8. In a device of the class described, the combination of a ring-like form of clamping me, provided mold therein, an equalizin I screen. for partially closing the opening in screen including a funnel shaped central portionprovided with an opening, and means or securing the screen to the frame.

9. A master mold construction] for use in conforming substantially with means for mounting'ak the frame, said forming work molds by electrolytic depgsit-ion, comprisin a master mold of para lic form outlined y a flan e rovided with a groove on the side thereo w ich has the concaved face of the mold, a ring of insulating material coated with a layer of conducting material located in said groove with a part 0 the ring exposed, and a clamp of insulating material temporarily securing the ring to the mold.

10. A master mold construction for use in formingwork molds by electrolytic de osition, comprising a master mold of para olic form outlined by a flange provided with a groove on the side thereof which has the concaved face of the mold, a ring of insulating material coated with a layer of conducting material located in said groove with a part of the ring exposed, a clamp of insulating material temporarily securing the ring to the mold, and an equalizing screen conforming substantially parallel thereto and provided at the crown of its parabolic portion with an aperturefacing the crown of the master mold.

11. A master mold construction for use in formingarticles by electrolytic deposition, comprising a master mold of parabolic form outline by a flange, a ring engaging one side of said flange, means for locating the ,ring accurately in prefixed position on the flange, and means for temporarily securing the ring in position.

"12. A master mold construction for use in forming articles by electrolytic deposition,

comprising a. master moldof parabolic form outlined by a flange, a ring engaging one side of said flange, means for temporarily secur- 'ing the ring in position, and an equalizing screen conforming substantially to the master mold, extending substantially parallel thereto and provided with an opening in spaced relation to said ring.

13. A master mold construction for use in forming articles by electrolytic de ition, com rising a master mold of parabo ic form by a flange, a ring engaging one side of said ing the ring in position, an equalizing screen to the master mold, extending substantially provided with an opening in spaced relation to said ring, and means distinct. from the ring securing means for temporarily securing the screen in place.

14. A mold/construction comprisinga mas- 15. A mold construction for use in an electrolytic bath, including a mold, a ring of in;-

sulating material having a metallic coating thereon engaging said mold, a clamp of insaid flange provided with,

parallel thereto and to the master mold, extending sulating material securing the ring to the mold and having one jaw engaging the side of the ring opposite the side engaging the mold thereby to limit the part of the ring exposed to the action .of the electrolytic bath.

16. A mold construction for use in forming articles electrolytically, including a mold,

a preformed frame of insulating material provided with a readily removable coating 10 of conducting material, mounted on the mold, and insulating means engaging the frame for stopping off the deposition from a part of the frame and for leaving the joint between the frame and mold exposed.

17 A mold construction including a metal mold having a part coated with an insulating material leaving a part exposed, and a preformed frame secured temporarily to the exposed part of the metal mold and having a portion of its surface coated with a layer of conducting material continuous with the exposed metal part of the mold whereby a layer of metal deposited electrolytically across the exposed port of the mold and the coated part of the frame will secure the frame to the layer of metal.

18. A mold for use in forming flanged parabolic reflectors, including a central parabolic portion outlined by an outstanding metallic flange, soldered on one side to the outstanding flange and having its exposed portions defined by-an insulating surface.

19. An article including a ring of insulating material having portions of its inner periphery rough and coated with metal, and an electrolytically deposited metal layer outv lined by said ring filling the space, within the inner periphery of thering and electrolytically soldered to the rough-metal coated portion of the inner periphery of the ring.

20. In a device of the class described, the combination of a rugged ring-like clamping frame provided with an inwardly extending a ring sh-apedeover plate fitted on top of the clamping frame and having an inwardly ex-- ged portion of the rame exteriorally of its seat and the portion of the'cover plate over-.

lapping the. same provided with circumfer-r A entlally' spaced registering screw holes,

clamping screws shanks passed through the holes and having -wide bearing heads and said exterior por- 95 cover plate coacting to enclose and protect.

having. threaded metal inforcing menl'ber therefor outlining the I groove, said layer and member secured by virtue of the interlocking engagement of the layer with said locking groove, and the major portion of the metal sheet being spaced from the said outlining reinforcing member.

23. An article including a sheet of metal "and a reinforcement for one edge of said sheet, said reinforcement comprising an insulating member, having one edge of the sheet electrolytically soldered thereto.

Signed at New York, in the county of New York and State of New York, this 20th day of October, A. D. 1926.

BLASIUS BART.

said flange outlined by a frame seat integral with the rugged ring-like frame,

tions of the nuts at opposite ends formed of insulating material and engaging said ex;

sheet of metal and provided with a locking lot 

